1. Field of the Invention
This invention relates to a novel liquid crystalline substance and a liquid crystal composition containing the same. More particularly it relates to a liquid crystalline substance containing an optically active group and a racemate thereof and further a chiral liquid crystal composition containing these.
The liquid crystalline substance referred to in the present invention includes not only compounds the liquid crystalline state of which can be observed by themselves, but also substances the liquid crystalline state of which cannot be observed by themselves, but which nevertheless have a chemical structure similar to that of the former compounds and are useful as a component constituting liquid crystal compositions.
2. Description of the Related Art
Twisted nematic (TN) type display mode has currently been most widely employed as liquid crystal display elements, but it is inferior in the response rate as compared with emissive type display elements such as electroluminescence, plasma display, etc., and various attempts for overcoming this drawback have been made, but, nevertheless, it seems that a possibility of improvement to a large extent has not been achieved. Thus, various liquid crystal display equipments based on different principles in place of TN type display elements have been attempted, and as one of them, there is a display mode utilizing ferroelectric liquid crystals (N. A. Clark and S. T. Layerwall, Applied Phys. Lett., 36,899 (1980)). This mode utilizes the chiral smectic C phase (hereinafter abbreviated to SC* phase) or chiral smectic H phase (hereinafter abbreviated to SH-phase) of ferroelectric liquid crystals, and these phases are preferred to be in the vicinity of room temperature. The present inventors have made various searches for liquid crystal substances containing an optically active group, mainly in order to develop liquid crystal substances suitable for being used for the above display mode, and as a result have attained the present invention.